What type of content (depth/breadth) is expected for a short presentation for Asst Professor interview in the UK?
While really short, 10 minute job talks in the UK are the standard and I actually think they work pretty well in that they do a good job of weeding people out. Sure, there were applicants that we turned down because they screwed up the job talk, but generally if the job talk went well, we were happy with the candidate. The best job talks accomplish 4 things.
First, they demonstrate ownership of your research. Many recent graduates were handed a PhD project and really never made it, or a portion of it, there own. Schools want to hire people that own their research. Talk about what your supervisor envisioned the project as being and how you transformed it into something even better.
Second, they frame the research in a way that makes it broadly accessible and highlights links to other members of the faculty. You don't need to hit the faculty member over the head, but you can talk about how your work on underwater basket weaving is important to consider when studying transportation of goods. During the Q/A portion of the talk, there is almost always a question about how your work relates to someone else's in the department. Alice may ask you how your work links with Bob's.
Third, they highlight which aspects of the technical details you have mastered and what things you still need to master. They will want to see that your current technical skills will allow you to pull off an interesting and funding worthy project. The best talks bring the audience to the weeds, acknowledge you are at the weeds and that you are happy to talk about them all day/night, all without actually going into the weeds. At the end of the talk you will inevitably get a probing technical question about some detail of your method from someone who has read your papers and understands what is going on (at least in a narrow scope). For these questions you apologize to the audience that you are about to jump into the weeds and give the technical answer.
The final thing is that they present a set of aims of the next research question. Ideally, the whole talk builds towards these so the faculty can see how your previous work leads to the aims and that your skill set will let you answer them. Even better is when a couple of other faculty can see ways to collaborate with you on the project. You do not need titles of sub projects or a timeline. Having identified a funding mechanism is always nice. You don't want to sound too independent at this stage, rather you want to come off as receptive to input and willing to modify the project to capture the strengths of the school. If there is a dinner/lunch afterwards, this will be the foundation of many of those discussions.
This answer is a bit speculative so use caution in accepting the advice. You have only a few minutes and they will slip by quickly.
I would focus on work in progress and on funding opportunities. If the audience is well familiar with your field, you could spend a bit of time on how you can appeal to grad students (whether as advisor or co-advisor). The time frame they are expecting you to cover is short, so work in progress is most important, but a mention of long term goals might get a short mention. If you use novel techniques or approaches that could be where you put any (short) bits of detail.
Also, it is probably worth saying a word or two about your ability to work cooperatively/collegially and your experience with it if you have any.
However, the word independent in the call is probably what they really want to hear about. Work in progress, again. You don't have much time for depth, though.
Try to give your talk at least once to a friend before the big day. You probably have too much information for 10 minutes. You want to know that beforehand.
And if this is a "cattle call" with four such talks in an hour, then you will need to find a way to stand out a bit from the crowd. Something positive that people might remember. But if the rest of the hour is for the faculty to ask questions, then you can be brief about a lot of things you mention.
Congratulations on your interview! Let me answer from the perspective of a current academic staff member at an institution like the one you describe. I'll give a few general points, rather than focusing on your questions individually. Of course, these are based on my personal experience and point of view, so don't take them as gospel.
First, be aware that 10 minutes is really short! Have you given a talk of this length before? If not, you may be surprised how little you can say in this space of time without rushing through things. Before worrying too much about fine details of what to say, try putting together a few slides and giving them a run-through at a comfortable pace. This will give you a better idea of how much you can fit in, and help you to prioritise your material. (Ideally, you should do this with someone listening.)
Second, know your audience. Your invitation email may or may not specify who you are going to be talking to, but if not, it's really worth writing back and asking for this information. If the audience is going to be made up of members of the research group that is hiring, then more technical detail may be appropriate; if the talk is open to (say) the whole Faculty of Engineering, you may want to give a more high-level talk.
Third, stick to your brief. If you are supposed to talk about "Your 3 year plan to become an independent academic", then focus on that. In particular, talking about grants that you plan to apply for is very much on-topic. Of course, you should make sure that the items you mention are realistic for someone at your career stage: a "plan" to win a £10 million Network grant from EPSRC (or whatever) is probably not going to impress anyone.
Good luck!